A conventional toroidal continuously variable transmission is known for example by published application Tokkai-Hei-10-148244 filed by the present applicant in Japan. This toroidal continuously variable transmission disposes power rollers between an input disk and an output disk. The contact radius of the input and output disks is varied by variation in the angle of gyration of these power rollers. In such a way, the ratio of rotation speed transmitted from the input disk to the output disk is varied.
The power rollers are supported to freely vary an angle of gyration by trunnions. These trunnions are driven in the axial direction by an actuator in order to vary a speed ratio. The actuator is operated on the basis of a speed ratio control signal calculated depending on vehicle operating conditions. The operation of the actuator is feedback controlled so that the speed ratio control signal equals the actual speed ratio.
When the speed ratio is varied, the trunnions displace in the axial direction by rotating about a shaft. The motion of the trunnions is feedback being controlled by a cam mechanism.
However when a large force is applied to the power rollers, the shaft of the trunnion which supports the power roller is deformed. When the shaft of the trunnion deforms, the contacting surface of the cam which feedback controls the motion of the trunnion varies. Lateral wear is generated on the contact surface as a result of the transmission of the motion not being smoothly performed by the cam and the contact being in an inclined position as a result.